Is Muse Spark Open open source?

Meta publishes the weights, but under its own Muse Model License. The license allows use, modification, distillation and sale, requires a "Built with Muse Spark Open" notice, and requires a separate agreement for Model as a Service businesses with more than $20 million in annual revenue.

How large is Muse Spark Open?

816B total parameters with 42B active per token, according to Meta's model card, plus a 1.8B-parameter perception encoder.

Muse Spark Open news

Open-weight multimodal language model2 stories

Muse Spark Open is an open-weight mixture-of-experts model from Meta, released on 15 October 2026 with 816B total and 42B active parameters and a 1M-token context window.

A long white data centre building behind pine trees and dry grass in central Oregon. — AMD and Meta put Helios racks into testing as AMD invests $1 billion in Meta

AI Chips & Infrastructure27 Oct 2026, 13:20 UTC

AMD said on 27 October 2026 that Helios racks are being tested at Meta, Meta will deploy a custom Instinct GPU, and AMD will invest $1 billion in Meta's equity.

Summary

AMD and Meta announced on 27 October 2026 an expanded partnership covering CPUs, GPUs, networking and software. Initial AMD Helios rack-scale systems are installed and being tested at Meta, Meta will deploy a custom Instinct GPU built for its workloads, and the companies are working on a future EPYC generation called Verano. AMD will also invest $1 billion in Meta's equity offering. No rack counts, gigawatt figures or dates are given.

Earlier stories

Meta releases Muse Spark Open, an 816B open-weight model under the Muse Model License
Open Source AI15 Oct 2026

About Muse Spark Open

Muse Spark Open is an open-weight mixture-of-experts model from Meta, released on 15 October 2026 with 816B total and 42B active parameters and a 1M-token context window. It accepts text, image, video and audio input, outputs text, and is licensed under the Muse Model License rather than a standard open-source license.

Reviewed 28 Oct 2026 · by Meta

Facts at a glance

Developer: Meta (Meta Superintelligence Labs)
Released: 15 October 2026 source
Parameters: 816B total, 42B active per token (256 experts, 8 active) source
Context window: 1M tokens source
Modalities: Text, image, video and audio input; text output
License: Muse Model License (attribution required; separate agreement for Model as a Service above $20M revenue)
Weights: BF16 and NVFP4 on Hugging Face (gated access) source
Hardware: At least 700GB of VRAM for NVFP4 and 2TB for BF16, per the model card source

More about Muse Spark Open (show)

What Muse Spark Open is used for

Meta describes Muse Spark Open as a natively multimodal model built for coding and agentic work, such as coding agents and customer service agents. The weights run in SGLang, vLLM, TensorRT-LLM, Hugging Face Transformers, Apple MLX, llama.cpp and Unsloth, and hosted inference is offered by providers including Baseten, Fireworks AI, Groq, Modal, Nebius, OpenRouter and Together AI. Meta says the model can run on two Mac Studio machines with M5 Ultra chips using MLX.

Questions people ask

Is Muse Spark Open open source?: Meta publishes the weights, but under its own Muse Model License. The license allows use, modification, distillation and sale, requires a "Built with Muse Spark Open" notice, and requires a separate agreement for Model as a Service businesses with more than $20 million in annual revenue.
How large is Muse Spark Open?: 816B total parameters with 42B active per token, according to Meta's model card, plus a 1.8B-parameter perception encoder.

Muse Spark Open news

Every story about Muse Spark Open

AMD and Meta put Helios racks into testing as AMD invests $1 billion in Meta

Earlier stories

Meta releases Muse Spark Open, an 816B open-weight model under the Muse Model License